Method of manufacturing an article by applying heat and pressure, a method of connecting a pipe to a sealed assembly and a connector for use therein

ABSTRACT

A method of manufacturing an article by diffusion bonding at least two metal components ( 30,36 ) comprises assembling the metal components ( 30,36 ) into a stack relative to each other so that the surfaces ( 34,40 ) are in mating contact. The edges of the metal components ( 30,36 ) are sealed together, except for an aperture ( 49 ) where a pipe ( 50 ) is to be connected. A connector ( 51 ) has a first end ( 52 ) and a second end ( 53 ). The first end ( 52 ) has a smaller diameter than the second end ( 53 ) and a bore ( 54 ) extends through the connector ( 51 ) from the first end ( 52 ) to the second end ( 53 ). The second end ( 53 ) of the connector ( 51 ) is joined ( 57 ) to the stack. The pipe ( 50 ) is joined ( 58 ) to the first end ( 52 ) of the connector ( 51 ). The interior of the sealed assembly is evacuated via the pipe ( 50 ) and the pipe is sealed. Heat and pressure are applied to diffusion bond the metal components ( 30,36 ) together to form an integral structure. The connector ( 51 ) reduces the possibility of failure of the pipe ( 50 ) and/or seal ( 57 ) during diffusion bonding.

The present invention relates to a method of manufacturing an article byapplying heat and pressure. The present invention relates to a method ofmanufacturing of article using a sealed assembly, which has beenevacuated by a pipe connected at a rigid point of attachment. Thepresent invention relates to a method of manufacturing a fibrereinforced metal matrix composite article, and the present inventionrelates in particular to a method of manufacturing a fibre reinforcedmetal matrix composite rotor, for example fibre reinforced metal matrixrings and fibre reinforced metal matrix composite discs. The presentinvention relates particularly to fibre reinforced metal matrixcomposite discs and fibre reinforced metal matrix composite rings whichare suitable for use in gas turbine engines as blade carryingcompressor, or turbine, rotors.

In one known method of manufacturing a fibre reinforced metal matrixcomposite article, as disclosed in European patent No. EP0831154B1, aplurality of metal-coated fibres are placed in an annular groove in ametal ring and a metal ring is placed on top of the metal-coated fibres.Each of the metal-coated fibres is wound in a plane and the metal-coatedfibre spirals are stacked in the annular groove in the metal ring. Themetal ring is pressed predominantly axially to consolidate the assemblyand to diffusion bond the metal rings and the metal-coated fibre spiralstogether to form an integral structure.

In a further known method of manufacturing a fibre reinforced metalmatrix composite article, as disclosed in European patent applicationNo. EP1288324A2, the arrangement described in EP0831154B1 is modified bythe inclusion of metal wires in the annular groove in the metal ringwith the metal-coated fibres. Each of the metal wires is wound spirallyin a plane and the metal wire spirals are stacked in the annular groovein the metal ring with the metal-coated fibre spirals.

In these methods of manufacturing a fibre reinforced metal matrixcomposite the assembly of metal rings and metal-coated fibre spirals, ormetal-coated fibre spirals and metal wire spirals, is sealed at theperiphery and junction of the metal rings to form a sealed assemblyprior to the diffusion bonding and consolidation process. The sealedassembly is evacuated via at least one pipe and the at least one pipe issealed before the diffusion bonding and consolidation process.

In these known methods of diffusion bonding and consolidation it isessential that there is a vacuum in the sealed assembly in order toensure that a satisfactory diffusion bond is formed between the metalrings and that the vacuum is maintained in the sealed assembly when theyare subsequently heated and pressed together during the diffusionbonding process.

However, there is a problem using this process because the heat andpressure applied during the diffusion bonding process causes the atleast one pipe to collapse/move whereas the metal rings are relativelylarge and rigid and do not/cannot move at the point of attachment of theat least one pipe. This collapsing/movement of the at least one piperelative to the metal rings may result in a failure/bursting of the atleast one pipe or a failure at the point of attachment of the at leastone pipe to the metal rings. The point of attachment of the at least onepipe to the metal rings usually comprises a weld seal and the weld sealmay fail during the diffusion bonding process. The failure of the atleast one pipe or failure of the weld seal results in a loss of vacuumin the sealed assembly and hence a failure to diffusion bond andconsolidate the sealed assembly. This may result in the scrapping of themetal rings and/or metal-coated fibre spirals, which may be high valuesub-components.

European patent No. EP0908263B1 discloses a method of manufacturing anarticle by diffusion bonding in which a pipe is angled relative to anaperture in a sealed assembly to reduce the possibility of failure ofthe pipe during diffusion bonding.

However, even this arrangement does not fully solve the problem becauseit is still possible for the pipe to move at its point of attachment,the weld, to the sealed assembly.

Accordingly the present invention seeks to provide a novel method ofmanufacturing an article by diffusion bonding.

Accordingly the present invention provides a method of manufacturing anarticle by applying heat and pressure comprising the steps of:

(a) joining a connector to a sealed assembly, the connector having afirst end and a second end, the first end having a smallercross-sectional area than the second end and a bore extending throughthe connector from the first end to the second end, joining the secondend of the connector to the sealed assembly,

(b) joining a pipe to the first end of the connector,

(c) evacuating the interior of the sealed assembly via the pipe,

(d) sealing the pipe with at least one seal,

(e) applying heat and pressure to the sealed assembly.

Step (a) may comprise assembling at least two metal components into astack relative to each other so that the surfaces are in mating contact,sealing the edges of the at least two metal components together, exceptfor an aperture where a pipe is to be connected, to form the sealedassembly and step (e) comprises applying heat and pressure to diffusionbond the at least two metal components together to form an integralstructure.

Preferably step (a) comprises forming a first metal component, forming asecond metal component, forming at least one fibre preform, the fibrepreform comprising at least one fibre, placing the at least one fibreand a filler metal between the first metal component and the secondmetal component, sealing the first metal component to the second metalcomponent and step (e) comprises applying heat and pressure such as toconsolidate the at least one fibre and the filler metal and to diffusionbond the filler metal, the first metal component and the second metalcomponent to form a unitary composite component.

Preferably step (a) comprises forming a groove in the first metalcomponent, placing the at least one fibre and filler metal in the groovein the first metal component and placing the second metal component inthe groove of the first metal component.

Preferably step (a) comprises forming a projection on the second metalcomponent and placing the projection of the second metal component inthe groove in the first metal component.

Preferably step (a) comprises forming a circumferentially extendinggroove in a face of the first metal component, placing at least onecircumferentially extending fibre and the filler metal in thecircumferentially extending groove of the first metal component andplacing the second metal component in the groove of the first metalcomponent.

Preferably the at least one fibre is a silicon carbide fibre, a siliconnitride fibre, a boron fibre or an alumina fibre.

Preferably the fibre is a metal-coated fibre.

Preferably the metal-coated fibre is titanium coated fibre, a titaniumaluminide coated fibre or a titanium alloy coated fibre.

Preferably the circumferentially extending fibre is a fibre preform.

Preferably the fibre preform is formed by winding at least one fibre ona former to form a spiral fibre preform.

Preferably the filler metal comprises at least one metal wire.

Preferably the metal wire is a wire preform.

Preferably the wire preform is formed by winding at least one metal wireon a former to form a spiral wire preform.

Preferably the at least one metal wire is a titanium wire, a titaniumaluminide wire or a titanium alloy wire.

The first end of the connector may have a larger cross-sectional areabore portion to receive the outer surface of the pipe.

Alternatively the first end of the connector receives the inner surfaceof the pipe.

Preferably the connector tapers from the first end to the second end.Preferably the connector tapers smoothly from the first end to thesecond end.

Preferably the connector is circular in cross-section.

Preferably the pipe is circular in cross-section.

Preferably the second end of the connector has a smaller cross-sectionalarea portion than the remainder of the second end and the smallercross-sectional area portion extends into the aperture in the sealedassembly.

Preferably the connector comprises a material softer than the at leasttwo metal components.

Preferably the sealing of the edges of the at least two metal componentsmay be by welding the edges of the at least two metal componentstogether.

Preferably the second end of the connector is joined to the sealedassembly by welding.

Preferably the pipe is joined to the first end of the connector bywelding.

The present invention also provides a connector to connect a pipe to asealed assembly, the connector comprising a first end and a second end,the first end having a smaller cross-sectional area than the second end,a bore extending through the connector from the first end to the secondend, the first end having means to receive the pipe and the second endhaving means to be received on the sealed assembly.

The first end of the connector may have a larger cross-sectional areabore portion to receive the outer surface of the pipe.

Alternatively the first end of the connector receives the inner surfaceof the pipe.

Preferably the connector tapers from the first end to the second end.

Preferably the connector tapers smoothly from the first end to thesecond end.

Preferably the connector is circular in cross-section.

Preferably the bore is circular in cross-section.

Preferably the second end of the connector has a smaller cross-sectionalarea portion and the smaller cross-sectional area portion extends intothe aperture in the sealed assembly.

Preferably the connector comprises a material softer than the sealedassembly.

The present invention also provides a method of connecting a pipe to asealed assembly, comprising joining a connector to a sealed assembly,the connector having a first end and a second end, the first end havinga smaller cross-sectional area than the second end and a bore extendingthrough the connector from the first end to the second end, joining thesecond end of the connector to the sealed assembly, joining a pipe tothe first end of the connector.

The first end of the connector may have a larger cross-sectional areabore portion to receive the outer surface of the pipe.

The first end of the connector may receive the inner surface of thepipe.

Preferably the connector tapers from the first end to the second end.

Preferably the connector tapers smoothly from the first end to thesecond end.

Preferably the connector is circular in cross-section. Preferably thebore is circular in cross-section.

Preferably the second end of the connector has a smaller cross-sectionalarea portion and the smaller cross-sectional area portion extends intothe aperture in the sealed assembly.

Preferably the connector comprises a material softer than the sealedassembly.

The present invention will be more fully described by way of examplewith reference to the accompanying drawings, in which:

FIG. 1 is a longitudinal, axial, cross-sectional view through a bladedcompressor rotor made according to the present invention.

FIG. 2 is a plan view of a fibre preform used in the method of thepresent invention.

FIG. 3 is a cross-sectional view through the preform shown in FIG. 2.

FIG. 4 is a longitudinal, axial, cross-sectional view through anassembly of fibre preforms positioned between first and second metalrings.

FIG. 5 is a longitudinal, axial, cross-sectional view through theassembly of fibre preforms positioned between first and second metalrings after welding together.

FIG. 6 is an enlarged cross-sectional view of a connector and pipe shownin FIG. 5.

FIG. 7 is an enlarged cross-sectional view of an alternative connectorand pipe shown in FIG. 5.

FIG. 8 is a longitudinal, axial, cross-sectional view through theassembly of fibre preforms positioned between first and second metalrings after consolidation and bonding to form a unitary compositearticle.

FIG. 9 is a plan view of a fibre and wire preform used in an alternativemethod of the present invention.

FIG. 10 is a cross-sectional view through the preform shown in FIG. 9.

A finished ceramic fibre reinforced metal rotor 10 with integral rotorblades is shown in FIG. 1. The rotor 10 comprises a metal ring 12, whichincludes a ring of circumferentially extending reinforcing ceramicfibres 14, which are embedded in the metal ring 12. A plurality of solidmetal rotor blades 16 are circumferentially spaced on the metal ring 12and extend radially outwardly from and are integral with the metal ring12.

A ceramic fibre reinforced metal rotor 10 is manufactured using aplurality of metal-coated ceramic fibres. Each ceramic fibre 14 iscoated with metal matrix 18 by any suitable method, for example physicalvapour deposition, sputtering etc. Each metal-coated 18 ceramic fibre 14is wound around a mandrel to form an annular, or disc shaped, fibrepreform 20 as shown in FIGS. 2 and 3. Each annular, or disc shaped,fibre preform 20 thus comprises a single metal-coated ceramic fibre 14arranged in a spiral with adjacent turns of the spiral abutting eachother. A glue 22 is applied to the annular, or disc shaped, fibrepreform 20 at suitable positions to hold the turns of the spiraltogether. The glue is selected such that it may be completely removedfrom the annular, or disc shaped, fibre preform 20 prior toconsolidation. The glue may be for example polymethyl-methacrylate indichloromethane (Perspex (RTM) in dichloromethane).

A first metal ring, or metal disc, 30 is formed and an annular axiallyextending groove 32 is machined in one radially extending axially facingface 34 of the first metal ring 30, as shown in FIG. 4. The annulargroove 32 has straight parallel sides, which form a rectangularcross-section. A second metal ring, or metal disc, 36 is formed and anannular axially extending projection 38 is machined from the secondmetal ring, or metal disc, 36 such that it extends from one radiallyextending axially facing face 40 of the second metal ring, or metal disc36. The second metal ring, or metal disc, 36 is also machined to formtwo annular grooves 42 and 44 in the face 40 of the second metal ring,or metal disc, 36. The annular grooves 42 and 44 are arranged radiallyon opposite sides of the annular projection 38 and the annular grooves42 and 44 are tapered radially from the face 40 to the base of theannular projection 38. It is to be noted that the radially inner andouter dimensions, diameters, of the annular projection 38 aresubstantially the same as the radially inner and outer dimensions,diameters, of the annular groove 32.

One or more of the annular fibre preforms 20 are positioned coaxially inthe annular groove 32 in the face 34 of the first metal ring 30. Theradially inner and outer dimensions, diameters, of the annular fibrepreforms 20 are substantially the same as the radially inner and outerdimensions, diameters, of the annular groove 32 to allow the annularfibre preforms 20 to be loaded into the annular groove 32 whilesubstantially filling the annular groove 32. A sufficient number ofannular fibre preforms 20 are stacked in the annular groove 32 topartially fill the annular groove 32 to a predetermined level.

The second metal ring 36 is then arranged such that the face 40confronts the face 34 of the first metal ring 30 and the axes of thefirst and second metal rings 30 and 36 are aligned such that the annularprojection 38 on the second metal ring 36 aligns with the annular groove32 in the first metal ring 30. The second metal ring 36 is then pushedtowards the first metal ring 30 such that the annular projection 38enters the annular groove 32 and is further pushed until the face 40 ofthe second metal ring 36 abuts the face 34 of the first metal ring 30,as shown in FIG. 5.

The radially inner and outer peripheries of the face 34 of the firstmetal ring 30 are sealed to the radially inner and outer peripheries ofthe face 40 of the second metal ring 36 to form a sealed assembly. Thesealing is preferably by TIG welding, electron beam welding, laserwelding or other suitable welding processes to form an inner annularweld seal 46 and an outer annular weld seal 48 as shown in FIG. 5.

A pipe 50 is then connected to an aperture 49 in the sealed assembly viaa connector 51, as shown more clearly in FIG. 6. The connector 51comprises a first end 52 and a second end 53, the first end 52 has asmaller cross-sectional area than the second end 53 and a bore 54extends through the connector 51 from the first end 52 to the second end53.

The first end 52 of the connector 51 has a larger cross-sectional areabore portion 55. The cross-sectional area of the bore portion 55 issubstantially the same as the cross-sectional area of the pipe 50 suchthat the outer surface of the pipe 50 may be received in the boreportion 55. The connector 51 tapers from the first end 52 to the secondend 53 and preferably the connector 51 tapers smoothly from the firstend 52 to the second end 53. The connector 51 is circular incross-section, the bore 54 is circular in cross-section and the pipe 50is circular in cross-section. The second end 53 of the connector 51 hasa smaller cross-sectional area portion 56. The smaller cross-sectionalarea portion 56 has substantially the same cross-sectional area as theaperture 49 such that the smaller cross-sectional portion 56 may beinserted into the aperture 49 in the sealed assembly to accuratelylocate the connector 51 relative to the first and second metal rings 30and 36. The connector 51 comprises a material softer than the first andsecond metal rings 30 and 36.

The portion 56 is inserted into the aperture 49 and the outer surface ofthe second end 53 of the connector 51 is sealed to the sealed assembly,second metal ring 36, by a weld 57. The pipe 50 is inserted into thebore portion 55 and the outer surface of the pipe 50 is sealed to thefirst end 52 of the connector 51 by a weld 58. The welds 57 and 58 arepreferably TIG welds.

The sealed assembly is evacuated using a vacuum pump and the pipe 50connected to the grooves, or chambers, 42 and 44. The sealed assembly isthen heated, while being continuously evacuated to remove the glue 22from the annular fibre preforms 20 and to remove the glue 22 from thesealed assembly.

After all the glue 22 has been removed from the annular fibre preforms20 and the interior of the sealed assembly is evacuated, the pipe 50 issealed at one or more positions using resistance welds. The sealedassembly is then heated and pressure is applied to the sealed assemblyto produce axial consolidation of the annular fibre preforms 20 anddiffusion bonding of the first metal ring 30 to the second metal ring 36and diffusion bonding of the metal on the metal-coated 18 ceramic fibres14 to the metal on other metal-coated 18 ceramic fibres 14, to the firstmetal ring 30 and to the second metal ring 36. During the application ofheat and pressure the pressure acts equally from all directions on thesealed assembly, and this causes the annular projection 38 to moveaxially into the annular groove 32 to consolidate the annular fibrepreforms 20.

The resulting consolidated and diffusion bonded ceramic fibre reinforcedcomponent is shown in FIG. 8, which shows the ceramic fibres 14 and thediffusion bond region 62. Additionally the provision of the annulargrooves, or chambers, 42 and 44 allows the annular projection 38 to moveduring the consolidation process and in so doing this results in theformation of a recess 63 in the surface of what was the second metalring 36. The recess 63 indicates that successful consolidation hasoccurred.

After consolidation and diffusion bonding the article is machined toremove at least a portion of what was originally the first metal ring30, at least a portion of the second metal ring 36 and at least aportion of the diffusion bonded region 62. In the example the majorityof the second metal ring 36 and the majority of the diffusion-bondedregion 62 is removed.

The article may then be machined for example by electrochemicalmachining or milling to form the integral compressor blades 16, as shownin FIG. 1, or the article may be machined to form one or more slots toreceive the roots of the compressor blades.

Alternatively, compressor blades may be friction welded, laser welded orelectron beam welded onto the article.

The advantage of the present invention is that during the diffusionbonding and consolidation, e.g. hot isostatic pressing, the connector 51progressively collapses but the seal, weld 57, between the connector 51and the sealed assembly does not fail and the seal, weld 58, between theconnector 51 and the pipe 50 does not fail. The welds 57 and 58 do notfail because the connector 51 tapers from the first end 52 to the secondend 53. The connector 51 is also made of a softer material. Theconnector 51 tapers gradually from the relatively rigid sealed assemblyto the collapsible pipe 50, thus the second end 53 of the connector 51is relatively rigid to match the sealed assembly and the first end 52 ofthe connector 51 is collapsible to match the pipe 50. Thus the welds 57and 58 are primarily vacuum seals, and need not be structural welds e.g.the welds 57 and 58 may be TIG welds rather than electron beam welds.

An alternative connector 51A, as shown in FIG. 7, comprises a first end52A and a second end 53A, the first end 52A has a smallercross-sectional area than the second end 53A and a bore 54A extendsthrough the connector 51A from the first end 52A to the second end 53A.

The first end 52A of the connector 51A receives the inner surface of thepipe 50A. The cross-sectional area of the first end 52A of the connector51A is substantially the same as the cross-sectional area of the innersurface of the pipe 50A. The connector 51A tapers from the first end 52Ato the second end 53A and preferably the connector 51A tapers smoothlyfrom the first end 52A to the second end 53A. The connector 51A iscircular in cross-section, the bore 54A is circular in cross-section andthe pipe 50A is circular in cross-section. The second end 53A of theconnector 51A has a smaller cross-sectional area portion 56A. Thesmaller cross-sectional area portion 56A has substantially the samecross-sectional area as the aperture 49A such that the smallercross-sectional portion 56A may be inserted into the aperture 49A in thesealed assembly to accurately locate the connector 51 relative to thefirst and second metal rings 30 and 36. The connector 51A comprises amaterial softer than the first and second metal rings 30 and 36.

The portion 56A is inserted into the aperture 49 and the outer surfaceof the second end 53A of the connector 51A is sealed to the sealedassembly, second metal ring 36, by a weld 57A. The inner surface of thepipe 50A is forced over the outer surface of the first end 52A and theouter surface of the pipe 50 is sealed to the connector 51 by a weld58A. The welds 57A and 58A are preferably TIG welds.

Before diffusion bonding and consolidation the assembly is sealed at oneor more positions by resistance welds. The connector 51A is sealed by aresistance weld radially through the pipe 50A and through the first end52A of the connector 51A and this forms the primary vacuum seal. Thepipe 50A is sealed by one or more resistance welds to provide additionalvacuum seals. The seal through the connector 51A minimises the risk ofvacuum failure due to failure of the thin walled large diameter pipe50A, it is to be noted that large diameter pipe 50A has to be thinwalled to enable it to collapse during diffusion bonding/consolidation.

The connector 51A has the same advantages as the connector 51 and inaddition the connector 51A provides better sealing of the pipe 50A.

The connector 51 is generally used for small diameter pipes e.g. 3 mmbore and 1.5 mm thick wall pipes and the connector 51A is generally usedfor larger diameter thin walled pipes.

The reinforcing fibres may comprise alumina, silicon carbide, siliconnitride, boron or other suitable fibre.

The metal coating on the reinforcing fibre may comprise titanium,titanium aluminide, titanium alloy, aluminium, aluminium alloy, copper,copper alloy or any other suitable metal, alloy or intermetallic whichis capable of being diffusion bonded.

The first metal ring and the second metal ring comprise titanium,titanium aluminide, titanium alloy, aluminium, aluminium alloy, copper,copper alloy or any other suitable metal, alloy or intermetallic whichis capable of being diffusion bonded.

Although the present invention has been described with reference tospirally wound metal coated fibres alone, the present invention is alsoapplicable to the use of fibre preforms 20A comprising spirally woundmetal-coated 18 ceramic fibres 14 and wire preforms 24A comprisingspirally wound metal wires 26, as shown in FIGS. 9 and 10. In FIGS. 9and 10 each fibre preform 20A is arranged in the same plane as anassociated wire preform 24A, but each wire preform 24A is at a greaterdiameter. The preforms 20A and 24A may be arranged in different planes.

Additionally the present invention is applicable to the use of spirallywound fibres and metal foils, spirally wound fibres and metal powder,helically wound fibres in metal ribbon, spirally wound fibres andspirally wound metal wires or other form of metal filler.

The metal wire may comprise titanium, titanium aluminide, titaniumalloy, aluminium, aluminium alloy, copper, copper alloy or any othersuitable metal, alloy or intermetallic which is capable of beingdiffusion bonded. The metal foil, metal ribbon, metal powder or othermetal filler may comprise titanium, titanium aluminide, titanium alloy,aluminium, aluminium alloy, copper, copper alloy or any other suitablemetal, alloy or intermetallic which is capable of being diffusionbonded.

In the example of titanium alloy metal rings, e.g. Ti 6 wt % Al 4 wt %V, the connectors may comprise commercially pure titanium, which issofter than the titanium alloy.

Although the present invention has been described with reference toproviding a circumferentially extending groove in a face of a firstmetal ring and a circumferentially extending projection on a face of asecond metal ring it is equally applicable to the provision of acircumferentially extending groove on a radially outer or inner face ofa ring. The present invention is also applicable to the use of aplurality of fibres, or metal-coated fibres, extending in a singledirection with the fibres, or metal-coated fibres, being arranged inlayers and with the layers being stacked upon each other.

The present invention is also applicable to any other arrangement wherethe fibres are placed between two or more metal components.

Although the present invention has been described with reference to themanufacture of fibre reinforced metal matrix composite articles, thepresent invention is also applicable to other manufacturing processes inwhich heat and pressure are applied to sealed assemblies, which havebeen evacuated by a pipe connected at a rigid point of attachment. Thusthe present invention is also applicable to other manufacturingprocesses which use diffusion bonding for example the manufacture ofdiffusion bonded articles, the manufacture of diffusion bonded andsuperplastically formed articles or the manufacture of hot isostaticallypressed articles e.g. for the consolidation of powder metal articles.The connector may be used to connect a pipe to a collapsible vacuum bagin which metal components, metal powder etc are placed to be diffusionbonded, brazed, consolidated, hot isostatically pressed etc. The pipe isconnected to the vacuum bag at a rigid point of attachment.

1-45. (canceled)
 46. A method of manufacturing an article by applyingheat and pressure comprising the steps of: (a) joining a connector to asealed assembly, the connector being generally tubular and having afirst end and a second end, the first end having a smallercross-sectional area than the second end and a bore extending throughthe connector from the first end to the second end, joining the secondend of the connector to the sealed assembly, (b) joining a pipe to thefirst end of the connector, (c) evacuating the interior of the sealedassembly via the pipe, (d) sealing the pipe with at least one seal, (e)applying heat and pressure to the sealed assembly.
 47. A method ofconnecting a pipe to a sealed assembly, comprising joining a connectorto a sealed assembly, the connector being generally tubular and having afirst end and a second end, the first end having a smallercross-sectional area than the second end and a bore extending throughthe connector from the first end to the second end, joining the secondend of the connector to the sealed assembly, joining a pipe to the firstend of the connector.